How to iterate numpy array (of tuples) in list manner

I am getting an error TypeError: Iterator operand or requested dtype holds references, but the REFS_OK flag was not enabled when iterating numpy array of tuples as below:

import numpy as np

tmp = np.empty((), dtype=object)
tmp[()] = (0, 0)
arr = np.full(10, tmp, dtype=object)

for a, b in np.nditer(arr):
    print(a, b)

How to fix this?

>Solution :

The error message actually tells you the problem and the fix: you’re attempting to iterate over an array of reference types (i.e. objects, dtype=object), but you didn’t enable np.nditer to iterate over reference types.

To fix that set the REFS_OK flag when calling np.nditer:

for x in np.nditer(arr, flags=["refs_ok"]):
    ...

Do note that there is also a second issue in your code. After making this fix, np.nditer is going to yield references a zero-dimensional array, which can’t be unpacked into a, b (even though that zero-dimensional array contains a 2-tuple). Instead, you can extract the tuple using .item() and and unpack it in the loop body:

for x in np.nditer(arr, flags=["refs_ok"]):
    a, b = x.item()